1.1 Technical Field
The present invention is directed to the treatment of age-related macular degeneration (ARMD) by the administration of certain antibiotics. In one embodiment, broad-spectrum bacteriostatic antibiotics, such as tetracycline-based antibiotics (TBA), are administered for up to fourteen (14) months, which leads to measurable improvements in some of the symptoms.
1.2 Background of Art
Age-related macular degeneration (ARMD) is the leading cause of blindness among persons over fifty in the United States and other countries (Bressler NM et al., Age-related macular degeneration. Surv. Ophthalmol. 1988; 32:375-413). Two forms of age-related macular degeneration are known: (1) neovascular, also known as exudative, age-related macular degeneration (E-ARMD) and (2) nonneovascular, also known as nonexudative, age-related macular degeneration (NE-ARMD). NE-ARMD is characterized by the presence of drusen, yellow-white lesions of the retinal pigment epithelium within the macula, and by other abnormalities of the retinal pigment epithelium, including retinal cell death.
Although the exact etiology of ARMD is not known, several risk factors seem to be important for the manifestation of this disease. For example, ARMD may be caused by chronic exposure of the retina to light. The presence or absence of certain nutrients in the diet, such as the antioxidant vitamins E and C, also may affect one's predisposition for ARMD. Other conditions, such as hypertension and smoking, are also considered to be important risk factors for the development of this disease.
Recent histopathologic studies show that leukocytes and chronic inflammation may play a role in the pathogenesis of atrophic NE-ARMD (Penfold PL et al., Senile macular degeneration: The involvement of giant cells in the atrophy of the retinal pigment epithelium. Invest. Ophthalmol. Vis. Sci. 1986; 27:364-371) and E-ARMD (Penfold PL et al., Age-related macular degeneration: Ultrastructural studies of the relationship of leucocytes to angiogenesis. Graefe's Arch. Ophthalmol. 1987; 2256:70-76).
Several therapeutic methods have been tried. For example, vitamins and dietary supplements have been used for the purpose of delaying the onset of disease. Thalidomide is being investigated to determine if it will slow down or arrest new vessel formation. Laser or radiation has been used to destroy new vessels. However, none of these methods has led to successful results and no definitive treatment for ARMD has been developed to date.